1. Field of the Invention
The present invention relates to a process for the purification of a gas mixture comprising a substantial amount of carbon dioxide by removal of hydrogen sulfide.
2. Description of the State of the Art
In the purification of gas mixtures, e.g., natural gas, by absorption to remove minor amounts of undesirable contaminants, it is desirable for highest gas purification to regenerate the absorbent to expel as much as possible of the contaminants to provide the leanest possible absorbent for recycle.
In conventional methods of purification of gas mixtures containing carbon dioxide and hydrogen sulfide, both gases are cosorbed by the absorbent (as high as 90% of the CO.sub.2 from natural gas) and in the desire to provide lean solvent recycle both are expelled to the greatest extent possible on regeneration, usually by steam stripping. This is true even when the gas to be treated comprises a major amount of carbon dioxide or is principally carbon dioxide gas.
It is desirable to effectively remove hydrogen sulfide from a gas mixture comprising a major amount of carbon dioxide without the cosorption of large amounts of carbon dioxide. It is also desirable (1) to reduce the operating temperatures of the absorption unit resulting in more selective hydrogen sulfide removal and (2) to reduce any steam requirements for regeneration of sorbent solution.